Signs having a snow-melting function for preventing degradation of visibility of the signs due to adhesion of snow are disclosed in Patent document 1, and so forth. The sign disclosed in Patent document 1 has a structure that a snow-melting unit is disposed on a surface of an LED display comprising a plurality of LEDs disposed in the form of matrix. The surface of the LED display is covered with an acrylic resin plate. The snow-melting unit has a configuration that two of acrylic resin plates other than that of the LED display are facingly disposed with a metal frame between them, and a heater in the form of cord is disposed in the internal space, and the sign has a configuration that this snow-melting unit is adhered to the acrylic resin plate on the surface of the LED display. When the heater is electrified, air in the internal space of the snow-melting unit is heated by the Joule heat generated by the heater and heat accompanying molecular motions caused by emitted far-infrared rays, and the acrylic resin plate is heated by the air. As a result, snow adhered to the acrylic resin plate can be melted.